This invention is directed to a method of expanding a collapsed carton for packaging machinery. Prior art machines utilize a single pivoted suction device which removes the lowermost carton of a stack of collapsed cartons and deposits the carton in the bucket of a conveyor by either stradling the conveyor or passing between a split conveyor. Means are employed between the stack and the conveyor to expand the carton. The speed of this type of machine is limited in that the suction device cannot be brought back to the stack of collapsed cartons until the carton moves out of the way. Attempts to solve this problem include the use of two or more elements to transfer the carton in different stages which greatly complicates the machine. One of the simplest of these mechanisms comprises a pair of spaced transfer wheels provided with cutouts. A pivoted suction device is used to extract the carton from the magazine and to deposit it within the cutouts of the transfer wheels. The carton is then transferred from the wheels to a conveyor bucket. Some variations in carton size can be accommodated by offsetting the cutouts of one wheel to the other, however, only a limited size range can be accommodated.
In addition to expanding the carton, the flaps at one end of the carton must be spread outwardly so that they do not interfere with the insertion of a product into the expanded carton. The flaps of the carton typically comprise two equal side flaps and a front flap which includes a tuck flap at the end thereof and which extends beyond the side flaps. Since the front flap extends beyond the side flaps it is relatively easy to employ a stationary cam surface for engaging the front flap and spreading it back as the expanded carton is advanced past the cam surface. However, the side flaps present a problem since they are of equal length. This problem is solved by employing a rotating or reciprocating member which is timed to wipe against one of the side flaps and spread it back as the expanded carton is being transferred from a stack to a conveyor. With one side flap spread back, it is then relatively easy to spread the other side flaps back by conveying the opened carton by a stationary cam surface as long as the carton is orientated so that the remaining side flap to be spread is the trailing flap of the moving carton.